debugger: deprecate built-in debugger

doc/api/debugger.markdown

@@ -1,9 +1,13 @@
 # Debugger
 
-    Stability: 3 - Stable
+    Stability: 0 - Deprecated
 
 <!-- type=misc -->
 
+Note: the built-in debugger is deprecated.  No new features will be added, bug
+fixes will be applied sparingly if at all.  Longer term, it will be moved out
+of node.js core and into a separate npm module.
+
 V8 comes with an extensive debugger which is accessible out-of-process via a
 simple [TCP protocol](http://code.google.com/p/v8/wiki/DebuggerProtocol).
 Node has a built-in client for this debugger. To use this, start Node with the

lib/_debugger.js

@@ -35,6 +35,9 @@ exports.start = function(argv, stdin, stdout) {
     process.exit(1);
   }
 
+  console.error('* The debugger is unsupported in this release.\n' +
+                '* Please see http://nodejs.org/docs/latest/api/debugger.html');
+
   // Setup input/output streams
   stdin = stdin || process.stdin;
   stdout = stdout || process.stdout;